For road rides too long for 3 water bottles (two in cages and one in center jersey pocket), I have no problem with using a Camelback.
The contention that it is "too uncomfortable" is nonsense. Less comfortable is true. But riding your bike is less comfortable that sitting on your couch, so why are you riding in the first place? Mountain bikers use Camelbacks all the time, and they (generally) ride much more slowly (less cooling from moving air, so sweaty back is more likely/more severe), and are moving around a lot more (Camelback is shifting around on their backs more). They put up with it because they are often far from a place where they can replenish fluids in their bottles, and running out of fluids is a LOT more "uncomfortable" than a little sweat on your back.
If you'd rather stop more frequently than carry a Camelback, then fine, that's a personal preference. I've used Camelbacks on many 4+ hour road rides, both summer and winter, with no issues - yes, my back is a little more sweaty, but it really isn't that big of a deal, I'm sweating all over anyway. I hate to stop during a ride, I'd rather keep going for 6 hours than have to stop every 2 or 3 hours to get more fluids. But, that's me.
If a Camelback works for you on road rides, I don't see a reason to stop.